Java AbstractSequentialList | add()

AbstractSequentialList uses the add() method specified by the List interface and overridden in class AbstractList. Hence AbstractSequentialList do not have a add() method of its own. Instead it has add(int index, E element) method.

AbstractSequentialList add(int index, E element) method inserts the specified element at the specified position in this list. It shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices). This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it inserts the specified element with ListIterator.add.

Therefore, add(E element) and add(int index, E element) both can be used with AbstractSequentialList class.

Syntax

public void add(int index, E element)

Parameters: This method takes two parameters:

• index – It represents the index, of type Integer, at which the specified element is to be inserted. This parameter is optional. If not specified, then the specified element is inserted at the last position in the list.
• element – It represents the element, of type E, to be inserted into the list.

Exceptions: This method throws following exceptions:

• UnsupportedOperationException – if the add operation is not supported by this list
• ClassCastException – if the class of the specified element prevents it from being added to this list
• NullPointerException – if the specified element is null and this list does not permit null elements
• IllegalArgumentException – if some property of the specified element prevents it from being added to this list
• IndexOutOfBoundsException – if the index is out of range (index size())

Below are the programs to illustrate add() method:

Program 1: Adding the elements, by without passing the index

// Java program to demonstrate
// add() method

import java.util.*;

public class GfG {

    public static void main(String[] args)
    {
        // Creating an instance of the AbstractSequentialList
        AbstractSequentialList<Integer> absl = new LinkedList<>();

        // adding elements to absl
        absl.add(5);
        absl.add(6);
        absl.add(7);

        // Printing the list
        System.out.println(absl);
    }
}

Output:

[5, 6, 7]

Java-CollectionsRemove term: Java-Functions Java-Functions
Program 2: Adding the elements, by passing the index

// Java program to demonstrate
// add() method

import java.util.*;

public class GfG {

    public static void main(String[] args)
    {
        // Creating an instance of the AbstractSequentialList
        AbstractSequentialList<Integer> absl = new LinkedList<>();

        // adding elements to absl
        absl.add(0, 8);
        absl.add(1, 7);
        absl.add(1, 9);
        absl.add(3, 10);

        // Printing the list
        System.out.println(absl);
    }
}

Output:

[8, 9, 7, 10]

Program 3: To demonstrate IndexOutOfBoundException

// Java code to show IndexOutofBoundException

import java.util.*;

public class GfG {

    public static void main(String[] args)
    {

        // Creating an instance of the AbstractSequentialList
        AbstractSequentialList<Integer> absl = new LinkedList<>();

        // adding elements to absl
        absl.add(5);
        absl.add(6);
        absl.add(7);
        absl.add(2, 8);
        absl.add(2, 7);
        absl.add(1, 9);
        absl.add(4, 10);

        // Printing the list
        System.out.println(absl);

        try {
            // showing IndexOutOfBoundsException
            absl.add(10, 12);
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

Output:

[5, 9, 6, 7, 10, 8, 7]
Exception: java.lang.IndexOutOfBoundsException: Index: 10, Size: 7